Improved butadiene-acrylonitrile copolymers



Patented Oct. 9, 1945 UNITED STATES PATENT OFFICE IMPROVED BUTADIENE-ACRYLONITBEE COPOLYMEBS Albert M. Clifl'ord, Stow, Cuyahoga Falls, Ohio,

Corporation, Akron, Delaware Ohio,

and William D. Wolfe. assignors to Wingioot a corporation of No Drawing. Application May 22, 1942,

Serial 1 Claim. (01.260-845) to form a useful cured rubber. Even prolonged milling has little eilect on its plasticity so that the attainment oi a smooth sheet is practica ly impossible. It has been recognized that ii the properties 01 synthetic rubbers of this type could be improved, the diiilculty and expense of making articles therefrom would be greatly reduced.

It has now been found that the workability oi butadiene-acrylonitrile type copolymers can be improved by incorporating in the mixture of monomers, to be subjected to polymerizing conditions, a quantity 01' an ester of alpha-substituted acrylic acid. Methyl methacrylate is the preierred modifier. The ester is added in monomeric term and therefore is interpolymerized with the other two monomers of the mixture. lnterpolymers prepared Irom the three constituents are found to be not, only more workable, being smoother and less grainy when worked, but also to yield vulcanizates of the copolymers prepared from the mere alone.

The process 01' polymerization is advantageously conducted in an emulsion, particularly an aqueous emulsion, so that the interpolymer is obtained as a coagulable latex. The ingredients ordinarily employed in such emulsiflcation polymerization are used, such as an emulsifying agent (tor instance, sodium lauryl suliate. sodium oleate and the like) and an oxidant (such as sodium perborate, hydrogen peroxide, etc.). The details or the emulsion polymerization are known in the art, being those employed in the manufacture or the two-component butadieneacrylonitrile copolymers. However, it may be said that agitation will be employed. and a temperature irom 30 to 80 C. will ordinarily preveil during the reaction. A preferred temperature range is in the neighborhood or 38-50 C. '1he acrylates which may be added for their modifying eflect on the inter-polymer include the two monobetter quality than itaconates which are alpha substituted acrylates having the formula 0 nl=c -o o 0 a Hr-C O 0 R Where It is a hydrocarbon substituent such as ethyl, butyl, etc., and also n-butyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, allyl methacrylate, terpinyl methacrylate, the corresponding ethacrylates, chlor acrylates, such as allyi alpha chloracrylate, etc.

The amount or the modifying acrylate ester which is added may vary from about 1% to 5% on the total monomer previously present in the reaction mixture, or as much as 10% may be The ratio of the butadiene and acrylonitrile may be varied in the usual proportion, such as. for example, '15 to 25, to 30, 80 to 40,. etc. Copolymers of this type are well-known in the art.

The butadlene-acrylonitrile type copolymer may be formed from butadiene-l,3 and acrylonttrlle, butadiene-l,3 and methacrylonitriie, isoprene and acrylonitrile, isoprene and methacrylonitriie and other suitable homologues oi butadiene and acrylcnitrile.

The copolymers may, [or example, be prepared according to the following formula:

' Butadiene pounds 6.0 Acrylonitriie -..do 2.0 Methyl methacrylate 1: Water -lbs 10.0 Sodium lauryl sulfate "grams" 220.0 Acetic acid --do 17.0 NaHaPO4 (anhydrous) ..-do- 40.! NaBOa do-- 80.0 Carbon tetrachloride do-.. 102.0 KCN -do 4.26 Acetaldehyde c.c- 11.6

The reaction vessel was evacuated and flushed with nitrogen, and the reaction was carried out at between 35 and 40 C. In three diflerent experiments the amount of methyl methacrylate employed was 0.8 pound, .16 and .4 pound being i, 2 and 5% respectively.

The latex thus produced may be coagulated with any usual coagulating medium, such as aleohol or barium chloride, etc.

The following table compares tests conducted under identical conditions on samples which are entirely comparable except that they contain different amounts or the methacrylate. The ratio of butadiene to acrylonitrile was :25 in all the test materials. The test results show that a. copolymer having improved properties is obtained.

Percent methyl me thacrylate 5222%? ggg fi {1 one 252 535 276 750 318 700 302 650 What we claim 1s:

CERTIFICATE OF C ORRECTION.

Patent No. 2,586,661.

October 9 1915 ALBERT M. CLIFFORD, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, sec- 0nd column, line 11.5, for "0.8" read --.O8--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 15th day of January, A. D. 19146.

(Seal) Leslie Frazer First Assistant Commissioner of Patents.

a. copolymer having improved properties is obtained.

Percent methyl me thacrylate 5222%? ggg fi {1 one 252 535 276 750 318 700 302 650 What we claim 1s:

CERTIFICATE OF C ORRECTION.

Patent No. 2,586,661.

October 9 1915 ALBERT M. CLIFFORD, ET AL.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 1, sec- 0nd column, line 11.5, for "0.8" read --.O8--; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 15th day of January, A. D. 19146.

(Seal) Leslie Frazer First Assistant Commissioner of Patents. 

